The present invention relates to a cribbing device for trenches consisting of supports which oppose each other in pairs and which are kept spaced apart by spreaders, and cribbing plates guided and supported in the supports in a form-locked manner. The supports have guiding profiles arranged next to each other vertically on crosspieces disposed transversely to the longitudinal axis of the trench. The guiding profiles engage the cribbing plates which are capable of being guided past each other on parallel planes. Furthermore, the guiding profiles arranged on each crosspiece of a support consist of equal legs standing vertically on the crosspiece of the support. Flange parts are vertically arranged with respect to the legs and are secured on the free ends of the legs. The width of the flange parts is slightly smaller than the inside width of the guide heads of the cribbing plates. The inside spacings between two adjacent crosspiece parts are slightly larger than the total width of the guide heads of the cribbing plates. The guide heads extend at the vertical face sides wholly or partially beyond the height of the cribbing plates and are designed in the form of sectionally outwardly open, slotted hollow box profiles (C-profiles). The position of the slot in the guide head conforms to the position of the crosspeice part of each guiding profile.
A cribbing device of this type is disclosed in German published patent disclosure DE-OS No. 29 49 312. With this device, it is possible to connect consecutively arranged cribbing plates of the above-specified type with a support in a form-locked way and to install such cribbing plates in the trench with stepwise displacement. With this known cribbing device, the spacing of the support is substantially preset and determined, or fixed.
In trench cribbing operations with cribbing plates of a large size, the situation may be such that the supports to be placed collide with transverse conduits such as, for example, building service lines, so that the cribbing series with large-sized plates is interrupted and small materials such as, for example, pile boardings or the like must be installed. Thus, it would be desirable to have available a simple means by which the cribbing length can be changed to accommodate such interferences.
This is all the more important with multistage cribbing operations. Furthermore, a cribbing may have to be constructed in places where phenomena of flow appear beneath the bottom stage, for example, in a two-stage cribbing, and where such phenomena require an additional cribbing stage possibly only over a short distance of the trench. As a rule, however, this cannot be achieved without the use of additional special cribbing materials.
Accordingly, it is an object of the present invention to provide a cribbing device which is adapted to provide a variable cribbing length and also an additional cribbing stage when required with a simple embodiment without the need to provide cribbing materials of varying lengths or types.
It is also an object of the present invention to provide such a cribbing device which can be used both for normal cribbing and which can also be used to provide for changes in the length of the spacing between two supports and/or changes in the cribbing depth.